Generally, a photosensitive plate to be used for relief printing plate consists of a support layer, a photosensitive resin composition layer, a coating layer and a cover film, and the cover film is removed when in use.
It is widely known that a relief printing plate can be prepared by exposing a photosensitive plate, from which a cover film has been removed, to actinic rays through a negative film (or positive film) having a transparent image part to cure a photosensitive resin layer of the exposed part, and removing a photosensitive resin layer of a non-exposed part by dissolving with a suitable solvent.
The recent request for a photosensitive plate to be used for a relief printing plate is directed to the reproduction of more micro-patterns, and a fine printing relief having a line width of void pattern of about 30 μm has been demanded. However, a relief printing plate material using a photosensitive resin composition cannot meet the request sufficiently and a photosensitive plate capable of reproducing fine patterns in plate making and printing has not been obtained heretofore. The present inventors have found that a coating layer of a photosensitive plate is involved in the reproducibility of fine pattern in plate making and printing. However, simultaneous achievement of the releaseability of a cover film during plate making and reproducibility of fine pattern in plate making and printing has been difficult.